The formulation of detergent compositions which effectively remove a wide variety of soils and stains from fabrics under wide-ranging usage conditions remains a considerable challenge to the laundry detergent industry. Challenges are also faced by the formulator of automatic dishwashing detergent compositions (ADD's), which are expected to efficiently cleanse and sanitize dishware, often under heavy soil loads. The problems associated with the formulation of truly effective cleaning and bleaching compositions have been exacerbated by legislation which limits the use of effective ingredients such as phosphate builders in many regions of the world.
Most conventional cleaning compositions contain mixtures of various detersive surfactants to remove a wide variety of soils and stains from surfaces. In addition, various detersive enzymes, soil suspending agents, non-phosphorus builders, optical brighteners, and the like may be added to boost overall cleaning performance. Many fully-formulated cleaning compositions contain oxygen bleach, which can be a perborate or percarbonate compound. While quite effective at high temperatures, perborates and percarbonates lose much of their bleaching function at the low to moderate temperatures increasingly favored in consumer product use. Accordingly, various bleach activators such as tetraacetylethylenediamine (TAED) and nonanoyloxybenzenesulfonate (NOBS) have been developed to potentiate the bleaching action of perborate and percarbonate across a wide temperature range. NOBS is particularly effective on "dingy" fabrics.
Despite the use of TAED and NOBS in various cleaning and bleaching compositions, the search continues for more effective activator materials, especially for cleaning additional types of soils and surfaces. Improved activator materials should be safe, effective, and will preferably be designed to interact with troublesome soils and stains. Various cationically charged activators have been described in the literature. Many are esoteric and expensive. Some do not appear to be sufficiently compatible with anionic surfactants to allow their easy formulation into detergent compositions and yield a truly effective surfactant-plus-activated bleach system. The majority of cationic activators in the literature have a conjugate acid aqueous pK.sub.a value of the leaving-group which is below 13. It is generally accepted that bleach activators having leaving-groups with pK.sub.a values below 13 perhydrolyze at a desirable rate.
It has now been determined that certain multiple-substituted bleach activators (MSBA's hereinafter) are unexpectedly effective in removing soils and stains from fabrics and hard surfaces such as dishes despite having a leaving-group conjugate acid aqueous pK.sub.a of greater than 13. These activators have advantageously high ratios of rates of perhydrolysis to hydrolysis and of perhydrolysis to diacylperoxide formation. Without being limited by theory, these unusual rate ratios lead to a number of significant benefits for the instant MSBA's, including increased efficiency, avoidance of wasteful byproduct formation in the wash, increased color compatibility, increased enzyme compatibility, and better stability on storage. Commercially attractive MSBA's are provided, for example through the use of caprolactam-based chemistry.
The MSBA's herein are effective for removing soils and stains not only from fabrics, but also from dishware in automatic dishwashing compositions. The MSBA's function well over a wide range of washing or soaking temperatures and are safe on rubber surfaces, such as those of sump hoses often used in European front-loading washing-machines. In short, the MSBA's herein provide a substantial advance over activators known in the art, as will be seen from the disclosures hereinafter.